Magnetic separators are one of the commonest particle separators that are used widely. They use a method of magnetically attracting and trapping iron scraps and the like with a magnet suspended from above, a magnet stored in a pulley of a conveyor, or magnets disposed on both sides of a flow path of particles, to thereby separate them from nonmagnetic particles. As the magnet, not only a permanent magnet, but also an electromagnet and a superconducting magnet may be used. In another method, a matrix made of iron thin lines is disposed between magnets in order for a magnetization gradient to be increased. Any of the methods are means for magnetically trapping particles and micro-particles having a weak magnetic property. As can be understood from above, the conventional magnetic separators aim for a technical goal of magnetically trapping as many particles as possible with a strong magnetic attractive force (a magnetic flux density or a magnetization gradient). There are few separators that are characterized by a weak magnetization property. However, PTL 1, for example, expressly describes an embodiment of such a weak magnetization property by means of reducing the sensitivity (a magnetic force) of a magnetic separator, but does not describe a specific apparatus and method. PTL 2 describes magnetic attraction of only ferromagnetic bodies with, like the present invention, a suspended magnetic separator that is placed at a distance from particles on a conveyor, but does not describe detailed conditions and performance thereof.
Meanwhile, shape separators include sensing sorters that distinguish the targets based on images monitored with a camera, mechanical separators utilizing rolling over an inclined surface, and gas stream separators using a shape as one of the separation factors. Mechanical shape separators include a centrifugal type, a vibration type, an inclined type, etc. Examples of inclined belt particle separators using a conveyor belt are described in PTLs 3 to 5.
Furthermore, there is an inclined belt separator combined with a magnetic separation function, which stores a magnet on the lower surface of the belt (see PTL 6).